1. Field of the Invention
The present invention relates to an iron core of a rotating-electric machine and, more particularly, to an iron core of a rotating-electric machine composed of laminated steel plates, and a manufacturing method for the same.
2. Description of the Related Art
FIG. 21 is a perspective view of a laminate used for an iron core of a conventional rotating-electric machine disclosed in, for example, Japanese Unexamined Patent Application Publication No. 48-9201. FIG. 22 shows a laminate of the iron core being formed by wrapping it around a cylindrical core member. FIG. 23 shows the formed iron core with its both end portions joined. A laminate 5 is fabricated by laminating a predetermined number of straight magnetic strips which are blanked out, and has a core proximal portion 5a and a plurality of teeth 5b equidistantly arranged. The laminate 5 that has been formed into a substantially hexahedral shape is wound with a winding (not shown), wrapped around a cylindrical core member 9 into a cylindrical shape, and an abutting portion 10 where both end portions thereof are abutted against each other is welded to join the end portions.
In the conventional iron core of a rotating-electric machine described above, as set forth above, a plurality of slots for accommodating the winding are formed in the magnetic strips, and the magnetic strips with the slots are stacked to form the substantially hexahedral laminate 5. The laminate 5 is wound around the cylindrical core member 9 to be shaped into a cylinder, and both end portions thereof are joined.
Such a conventional iron core 40 of a rotating-electric machine is not a cylindrical iron core from the start. Winding work can be facilitated by wrapping a winding (not shown) around the substantially hexahedral laminate 5. There is an advantage in that, since the laminated 5 is curved after installing the winding, a sectional area of a slot after curving becomes smaller than that before curving, thus allowing the winding to be disposed at a higher density.
On the other hand, in the case of the conventional iron core 40 of the rotating-electric machine having the construction described above, portions in the vicinity of both end portions are formed to have larger-radius curves than a curve of the remainder thereof, so that joining surfaces of the abutting end portions do not snugly meet, leading to unsuccessful joining when the virtually hexahedral laminate 5 is wrapped around the cylindrical core member into a cylindrical shape. More specifically, the curves near the abutting portion 10 are insufficient, and a curvature radius is uneven over an entire circumference, presenting a problem in that joining surfaces are misaligned, resulting in unsuccessful joining.
There has been another problem in that forcibly meeting the abutting portion 10 deteriorates the roundness of the iron core.
Furthermore, in the conventional iron core 40 of a rotating-electric machine having the above construction, there has been still another problem in that wavy deformation as shown in FIG. 24 occurs when the iron core 40 is cylindrically wound around the cylindrical core member 9.
There has been yet another problem in that bending rigidity at both end portions of the virtually hexahedral laminate 5 is high, and a large force is required for curving the end portions, causing a tooth portion 5b to buckle.
Accordingly, the present invention has been made with a view toward solving the problems described above, and it is an object thereof to provide an iron core of a rotating-electric machine capable of allowing a curvature of the iron core to be easily made uniform over its entire circumference, permitting roundness of the cylindrical iron core to be improved, preventing the occurrence of wavy deformation and also preventing a tooth portion from buckling or deforming, allowing a reduced space between a magnetic pole or a magnet opposing the iron core to be achieved, allowing lower magnetic resistance of an air gap, and permitting an output of the rotating-electric machine to be increased. Another object of the present invention is to provide a manufacturing method for the iron core of the rotating-electric machine described above.
To this end, according to one aspect of the present invention, there is provided an iron core of a rotating-electric machine, which iron core is constructed by laminated magnetic plate strips; a cylindrical core proximal portion; a plurality of teeth projecting in a substantially radial direction from the core proximal portion; and slots for accommodating a winding that are located between the teeth adjacent to each other, wherein the iron core is fabricated by curving both end portions of a substantially hexahedral laminate so that the core proximal portion obtains a predetermined curvature, forming the entire laminate into a cylindrical shape by wrapping it around a cylindrical core member so that distal ends of the teeth project from the core proximal portion, and joining both end portions of the laminate.
In a preferred form, both end portions of the core proximal portion of a laminate have a lower rigidity than that of the remainder thereof.
In another preferred form, both end portions of the core proximal portion of the laminate are provided with thinner portions that are thinner in a radial direction so as to have a lower rigidity.
In yet another preferred form, a filling member for making a diameter of a circumferential end portion of the core proximal portion identical to that of the remainder is welded to the thinner portions.
In still another preferred from, both end portions of the core proximal portion of the laminate are formed so that the diameter of the circumferential end portion of the core proximal portion becomes smaller toward and end thereof so as to reduce the rigidity thereof.
In a further preferred form, both end portions of the core proximal portion of the laminate are provided with at least one notch each at a location adjacent to the circumferential end portion of the core proximal portion so as to reduce the rigidity thereof.
In a further preferred form, the iron core of the rotating-electric machine is formed by curving a single virtually hexahedral laminate.
According to another aspect of the present invention, there is provided a manufacturing method for an iron core of a rotating-electric machine, the iron core including laminated magnetic plate strips, a cylindrical core proximal portion, a plurality of teeth projecting in a substantially radial direction from the proximal core portion, and slots for accommodating a winding that are located between adjoining teeth, the manufacturing method including: an end portion curving step for curving both end portions of a substantially hexahedral laminate of the iron core so that the core proximal portion obtains a predetermined curvature; a body curving step for curving the entire laminate into a cylindrical shape by wrapping it around a cylindrical core member so that distal ends of the teeth project from the core proximal portion; and a joining step for joining both end portions of the laminate.
In a preferred form, the laminate is clamped between a first fixing jig disposed at the core proximal portion and a second fixing jig disposed at the teeth such that the end portions project by a predetermined length, and the end portions of the laminate are curved by pressing the end portions in a direction in which the teeth project by a pressing jig in the end portion curving step, an end portion of the second fixing jig that is adjacent to the teeth being provided with an arc or linear slope that becomes farther from the teeth toward an end thereof.
In another preferred form, the laminate is clamped between a first fixing jig disposed at the core proximal portion and a second fixing jig disposed at the teeth such that the end portions project by a predetermined length, and a closely contacting jig having an L-shaped section is placed in close contact with a corner of the core proximal portion of the end of the laminate, and the end portions of the laminate are curved using the closely contacting jig such that they are wrapped toward the teeth, an end portion of the second fixing jig that is adjacent to the teeth being provided with an arc or linear slope that becomes farther from the teeth toward an end thereof.
In a further preferred form, the iron core is formed by curving a single laminate having a substantially hexahedral shape, and the body curving step includes: a first body curving step in which a central portion of the laminate is clamped, and both end portions of a predetermined length from ends are wrapped around a cylindrical core member; and a second body curving step in which the curved portions that have been formed in the first step are clamped and the remaining central portion is curved by wrapping it around the core member.
According to still another aspect of the present invention, there is provided a manufacturing method for an iron core of a rotating-electric machine constructed by laminated magnetic plate strips, a cylindrical core proximal portion, a plurality of teeth projecting in a substantially radial direction from the core proximal portion, and slots for accommodating a winding that are formed between the teeth adjacent to each other, the manufacturing method including: a body curving step for wrapping a central portion of a laminate around a cylindrical core member to form the laminate into a cylindrical shape such that distal ends of teeth project from the core proximal portion; an end portion curving step for clamping the laminate, which has been curved in the body curving step, at inner and outer peripheries except end portions thereof and curving the end portions of the laminate by pressing or wrapping the end portions toward the inner periphery thereof; and a joining step for joining both end portions of the laminate.
In a preferred form, the manufacturing method includes a step for accommodating a winding in slots of the substantially hexahedral laminate before at least the body curving step, and the body curving step is implemented with the winding accommodated in the slots.
In a further preferred form, the body curving step is carried out while at least a part of the core proximal portion of the laminate is slidably guided from both sides.